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Abstract: Sputtered coating of a low-Cr Fe–Co–Ni alloy with 0.36wt.% Si has been prepared on the same cast alloy via magnetron sputtering method. The sputtered low-Cr alloy coating with columnar nanocrystalline structure is thermally oxidized in air at 800°C corresponding to the cathode atmosphere of solid oxide fuel cell (SOFC). It is found that the oxidation resistance of the sputtered low-Cr alloy coating is significantly improved in comparison with the cast low-Cr alloy. A double-layer oxide scale is thermally developed on the sputtered low-Cr alloy coating after oxidation for 12 weeks. The outer layer is (Co,Fe)3O4 spinel containing small amount of Ni and Cr. The inner layer is a continuous Cr2O3 layer, followed by oxides of CrNbO4 and Nb2O5. The surface scale formed on the sputtered coating after 12-week thermal exposure demonstrates an area specific resistance (ASR) of 31.97mΩcm2. The sputtered low-Cr alloy nanocrystaline coating exhibits a promising perspective for intermediate temperature SOFC interconnects application. [Copyright &y& Elsevier]

Abstract: The nanocrystalline coating of a low-Cr Fe–Co–Ni base alloy with 0.36wt.% Si was deposited on the as-cast low-Cr alloy with identical compositions by means of magnetron sputtering. The effect of sputtered columnar nano-grain structure on the oxidation behavior of the low-Cr alloy was investigated in air at 800°C. It was found that the columnar nano-grain structure significantly lowered the oxidation rate and changed the surface oxide structure of this alloy. The formation of a continuous Cr2O3 inner layer beneath the CoFe2O4 spinel outer layer on the sputtered nanocrystalline coating resulted in a remarkable improvement in oxidation resistance compared to the cast low-Cr alloy. [Copyright &y& Elsevier]